This research is directed to understanding the mechanism by which Nesseria gonorrheae, the causitive agent of gonorrhea, stimulates and possibly evades the immune response occurring at mucosal surfaces. The secretory immune apparatus, in which the genito-urinary tract participates, is an IgA mediated system. N. gonorrheae produces an extracellular enzyme, IgA protease, that attacks human IgA antibody protein to proteolytically cleave the molecule, thereby rendering it inactive or inefficient in its antibody function. Experiments involve the characterization of gonococcal IgA protease, the study of the production of this enzyme by the organism when binding to human tissues, and the effect of the antibody on the biological properties of secretory IgA. In addition, we are attempting to characterize antibodies produced by human beings in response to the enzyme as antigen, these antibodies are inhibitory to the proteolytic activity of the IgA protease and may counter its immuno-destructive properties.